Title

Alternative Title

Civil Engineering Study 79-1

Abstract

INTRODUCTION In the design of steel buildings, the "Allowable Stress Criteria" have long been used for the design of cold-formed steel structural members in the United States (1), Canada (2) and other countries (3). Even though the theoretical concepts of risk and reliability analyses have been available for some time (8-10) and the slgnlflcance of such concepts in structural safety and design is well recognized, the probabilistic method has not been explicitly adopted as a basis for the American design standard for steel structures. In view of the fact that the mathematical theory of probability, which has been so successfully applied in other fields of engineering, would seem to be equally applicable to cold-formed steel design by providing a more uniform degree of structural safety, the "Limit States Design", which is based on the probabilistic concept, was introduced in the Canadian Standard on the Design of Cold-Formed Steel Structural Members in 1974 as an alternate to existing procedures for design calculations of building structures (4-7). Recently, the "Load and Resistance Factor Design Criteria for Steel Buildings" have also been studied by T.V. Galambos and M.K. Ravindra (11,12) However, this study deals only with the design of hot-rolled shapes and built-up members fabricated from steel plates that are currently designed on the basis of the AISC Specification (13). In order to develop the new design criteria for cold-formed steel structural members based on the probabilistic approach, a research project entitled "Load and Resistance Factor Design of Cold-Formed Steel" was initiated in January 1976. This study is being conducted by Trinh Ngoc Rang under the direction of Wei-Wen Yu. Ted V. Galambos and M.K. Ravindra are the consultants for the first phase of the project. This progress report contains a description of the objective and the planned program in Article II. The progress that has been made on the development of the load and resistance factor design of cold-formed steel is discussed in Article III. Article IV deals with the plans for future studies. This report is a revision of the First Progress Report dated June, 1976. This investigation was conducted under the sponsorship of American Iron and Steel Institute. The technical guidances provided by our consultant, Dr. M.K. Ravindra, the AISI Task Group on Load and Resistance Factor Design (K.H. Klippstein, Chairman, D.H. Hall, R.B. Matlock, and D.S. Wolford, members), the advisors for the AISI Task Group (R. Bjorhovde, N.C. Lind, F.J. Phillips, C.W. Pinkham, and G. Winter) and the AISI Staff (A.L. Johnson and D.P. Cassidy) are gratefully acknowledged. Thanks are also due to J.H. Senne for his advice during the project. Special thanks are extended to Mrs. Sandra Palmer and Sue Salomon for typing this report.